Percussive tool



April 9, 1929. A. MULLER I 1,708,451

PERCUSSIVE TOOL Filed Aug. 8, 1925 v m Elk M jliiilq 9, 1929.

UNITED STATES PATENT! OFFICE.

AUGUST Ml'J LLER, OF BERN, SWITZERLAND; ERNST VI'YSS ADMINISTRATOR OF SAID MllLLER, DECEASED, ILSSIGNGR TO THE SWITZERLAND.

FIRM ELEKTRO-HAMMER A. G., OF BERN,

PERCUSSIVE TOOL.

Application filed August 8, 1925, Serial No.

This invention relates to improvements in porous c tools of the type in which a spring is periodically engaged and released by a curved member.

The hitherto known tools of this type were so constructed, that the angle of inclination of the curved member was always constant at every moment. The torque on the curved member which is required to put the spring under tension is:

T 0 tun (who) drivin torque can be utilized completely only at the moment when the spring is under maximum tension.

T he present invention aims at overcoming this drawback ind provides a percussive tool ot the aforesaid type in which the curved member adapted to engage and release the spring, is constructed in such a manner that the product of the resistance of the spring (or springs) and the distance through which the striker has been lifted (taking into ac- I c mt the eliiciency corresponding to the ideal inclined plan-o the time 1 n viz, tan

(orio) alw s remains a e is obvious that instead of a single spring, a plurality ot' s ngs m y be employed to o the same ct. 7 p e oi 'ir assumed i r definite conditions, it is possible to determine from the above equation, the corresponding angle of inclination a for the torque T at every moment.

Fercussive tools which are constructed in this manner, will, with the same driving force, yield nearly twice the output of other tools. v r 7 By thus uniformly loading the source of driving energy during the compression of the spring or springs not only is said source 49,118, and in Switzerland March 23, 1925.

of energy, but also the entire mechanism carefully preserved; moreover the efliciency of the e tire tool from the source of power to the blow becomes about twice that of the aforesaid known apparatus, that is to say it is possible to produce the same percussive output. with only half the driving energy of a percussive tool having a spring-tensioning cam member exhibiting a constant angle of inclination.

in order to more clearly understand the inention, reference is made to the accompany- 1i drawings which illustrate by way of exon ple one embodiment thereof, and in which:

Fig. 1 is a longitudinal section, and

2 a tension curve.

In Fig. 1, 1 indicates a cam member,whichis mounted upon the fixed spring support 4 by means of the ball bearings 2 and 8 and is driven by the pinion shaft 5. The driver 6,fixed on tha iper bar a, which glides upon the cam menoer l is guided by means of the guide 8 with the aid of the ball bearings and collar 7 shaft, for example by an electric motor which i can be connected to a direct or alternating currentelectric lighting network.

The shaft 5 may be driven from a distance by any suitable means through a flexible shaft for example by an electric motor which can be connected to a direct or alternating current electric. lighting network.

H 111g now particularly described and ascertained the nature of my said invention and in what manner the same is to be pertermed, I declare that what I claim is:

.i r a percussive tool embodying a reciprocating percussive member and a compression spring adapted to normally lower the percussive member, a curved operable member adapted to periodically elevate and abruptly release the percussive member having an angle of slope varying according to the formula a= arc tan a. 

